The invention relates to insulating materials; it relates, more particularly, to an interconnected, expandable structure composed of laminated membranes incorporating at least one layer of a flexible material of poor thermal conductivity and at least one layer of reflective metal foil.
The art of constructing insulation adapted to be disposed between a source of heat and a sink for same, is old; all habitable structures are designed to keep the internal volume of the structure cooler, or warmer, than the surrounding atmosphere. All walls surrounding such structures are, therefore, constructed to exhibit as low a thermal transmission capacity as may be compatible with the materials employed and economic costs and benefits predicted.
In particular, it is known to utilize a material provided with internal subdivisions so as to reduce the direct heat conductivity paths, and to suppress the tendency of the gases trapped in the subdivisions towards natural convection heat transfer. Such commonly employed insulating materials as mineral wool, glass fiber batts, plastic and elastomeric foams, low-density ceramics and others operate on the principle of defining a volume with the least possible solid mass and the separation of the air entrapped in the structure into independent convective cells.
It is also well-known that reflective surfaces, such as bright metallic foils, have a tendency to reflect incident radiant heat, a form of electromagnetic radiation, towards the source. The combination of the aforementioned insulating techniques is also known, as for example in the provision of commercial glass fibre insulation in paper-enclosed batts with one surface composed of, or laminated with, an aluminum foil surface. Such materials are commonly installed in the walls of structures with stud walls and provide a barrier to all three forms of heat transfer; conduction, convection and radiation.
The prior art includes insulating panels or assemblies in which a semi-rigid sheet material, typically paper, is employed to form a cellular structure in the form of a panel. The cells formed in such structure may be filled with a fibrous insulation, or with a rigid, castable material, or may be left filled with entrapped air. Such structures of the prior art are described in U.S. Pat. No. 1,914,207 to KNIGHT; U.S. Pat. No. 1,942,989 to THOMSON; U.S. Pat. No. 2,098,193 and U.S. Pat. No. 2,417,435 to MUNTERS; and U.S. Pat. No. 2,662,043 to CLEMENTS.
Typically, the structure of the prior art are employed in the form of light-weight panels whose transportation to the user and installation in the field both require extensive labor and affect their economic utility. Furthermore, while such structures are capable of reducing the conductive and convective heat transfer modes, they generally fail to provide effective means for interdicting radiant heat transmission.
It is the primary object of the invention to provide an improved heat transfer barrier structures with substantially polygonal cells defined by impermeable membranes laminated from at least one layer of an insulating sheet and one layer of a reflective foil.
It is an object of the invention to teach the construction and use of insulating structures with the foregoing characteristics, which may be transported in a collapsed condition and expanded by the user into the final configuration.
It is an additional object of the invention to define an insulating structure which retains its insulating properties over a wide range of linear expansion from its contracted or collapsed condition and which, furthermore, allows the structure to conform to substantial radii of curvature in two mutually orthogonal planes, so as to allow its use and installation in irregular spaces and about curvilinear and other shaped objects.